Water Tube Boilers

Water tube boilers are designed to circulate hot combustion gases around the outside of a large number of water-filled tubes. The tubes extend between an upper header, called a steam drum, and one or more lower headers or drums. In older designs, the tubes are either straight or bent into simple shapes.

Newer boilers have tubes with complex and diverse bends. Because the pressure is confined inside the tubes, watertube boilers can be fabricated in larger sizes and used for higher-pressure applications. Small watertube boilers, which have one and sometimes two burners, are generally fabricated and supplied as package units. Because of their size and weight, large watertube boilers are often fabricated in pieces and assembled on site. Almost any solid, liquid or gaseous fuel can be burned in a watertube boiler. Common fuels include coal, oil, natural gas, biomass, and other solid fuels such as municipal solid waste, tire-derived fuel and rdf.